This invention relates generally to ultrasound imaging, and more particularly to detecting and indicating differences in tissue within an ultrasound image.
With current ultrasound imaging it is difficult to detect tissue properties such as tissue elasticity, stiffness, morphology or type. Tissue elasticity varies, for example, between different types of tissue, such as hard and soft plaque within the carotid artery. Also, a tumor or other mass will have tissue elasticity that is different compared to surrounding tissues. Having the ability to detect the elasticity or stiffness differences would improve the ability to detect dangerous plaque as well as other pathologies.
Shear modulus is a parameter related to the hardness or elasticity of a material or tissue. The shear modulus of various soft tissues ranges over several orders of magnitude. Previous methods for imaging elastic properties with ultrasound, such as radiation force ultrasound, rely on high amplitude, low frequency acoustic radiation fields or external vibration sources to generate shear waves in the tissue. Examples of imaging techniques are tissue velocity imaging (TVI) and strain imaging. Other techniques use multiple ultrasound transducers, thereby increasing the cost and complexity of a procedure.
Therefore, a need exists for detecting elasticity properties of tissues and indicating elasticity differences using standard ultrasound imaging with a single ultrasound probe.